1. Field of the Invention
This invention relates to collapsible umbrellas and in particular to collapsible umbrellas having detachable fabric tops stretched over bowed ribs.
2. Description of the Prior Art
Hand-held personal umbrellas have long been used for protection against the elements and also as fashionable accessories used to compliment or contrast with clothing. Most of the patents representing the umbrella art are directed toward making the hand-held umbrellas more compact when the ribs and cover are not extended. In contrast, little attention has been paid to utilizing new materials and construction methods for producing larger umbrellas, such as those used to provide shade and those used upon the beach. In these designs, the compactness of the umbrella is a secondary consideration when compared to the requirements of durability and freedom from mechanical failure. In particular, these recent advances have not been incorporated into umbrellas specifically designed to operate in adverse environmental conditions, such as exposure to the intense sunlight present in the tropical climates and exposure to salt water and the salt water atmosphere commonly encountered when the umbrellas are used on the beach.
A hand-held collapsible umbrella utilizing a metallic shaft and a rib structure covered by a fabric shield is disclosed by DeWitt in U.S. Pat. No. 992,861. The DeWitt umbrella utilizes a tip cap having a recess therein for restraining the ball ends of the plurality of ribs forming the umbrella frame. Edwards, in U.S. Pat. No. 959,127 discloses a somewhat different method of retaining a ball located at a distended end of the rib structure, within a restraining device. Goldstein, in U.S. Pat. No. 2,350,227 discloses the use of a ferrule accessory for coupling the center section of the fabric top to the tip of the shaft. Dubinsky, in U.S. Pat. No. 3,431,926 and Jones in U.S. Pat No. 2,531,735 illustrate various methods for using sections of the fabric cover for coupling directly to the distended ends of the umbrella ribs. Farkas, in U.S. Pat. No. 2,087,756, discloses the use of U-shaped clips for securing the cover to sections of the ribs intermediate the ends thereof. See also U.S. Pat. No. 2,746,469 issued to D'Andrea, U.S. Pat. No. 940,346 issued to Morton and U.S. Pat. No. 422,643 issued to Shaw.